Two novel approaches for preventing stroke in patients with nonvalvular atrial fibrillation proved more cost-effective than warfarin in an economic evaluation published online May 22 in Circulation, with percutaneous left atrial appendage (LAA) occlusion beating out dabigatran for value.
At HRS.13, four-year results from PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) found the Watchman LAA occlusion system (Boston Scientific) to be superior to warfarin for efficacy and mortality in patients with nonvalvular atrial fibrillation who are at risk of stroke. In RE-LY (Randomized Evaluation of Long-term anticoagulation therapY), the anticoagulant dabigatran (Pradaxa, Boehringer Ingelheim) at 110 mg showed similar rates of stroke and systemic embolism as warfarin and lower rates of major hemorrhage; at 150 mg, it had lower rates of stroke and systemic embolism but similar rates of major hemorrhage. A U.K. analysis also ruled that dabigatran was cost-effective.
Sheldon M. Singh, MD, of the Schulich Heart Centre in Toronto, and colleagues wanted to evaluate how the two novel treatments stacked up against warfarin in a cost-utility analysis. Using a Markov model and data from PROTECT-AF, RE-LY and Canadian cost resources, they calculated and compared the projected quality-adjusted survival and costs of LAA closure devices, dabigatran and warfarin. Costs were in 2012 Canadian dollars and the analysis was from the perspective of a third-party payer.
They used CHA 2DS2VASc and HAS-BLED scores for simulated patients with a base age of 76 to predict stroke and bleeding, and updated each cycle to reflect increasing age and changes in risk factors. Health outcomes and costs were discounted 5 percent per year.
Based on a lifetime analysis, major stroke rates for patients on warfarin, dabigatran and LAA occlusion devices were 16.5 percent, 17.3 percent and 17.4 percent, respectively. Each approach had a degree of treatment discontinuation: 16.3 percent of patients on warfarin, 20.5 percent for dabigatran and 9.3 percent of LAA occlusion patients had an unsuccessful implantation. Of those with a successful implantation, 12.2 percent developed residual leak at six weeks and needed warfarin for another 4.5 months and 7.1 percent had residual leak at six months and needed warfarin indefinitely.
The discounted life expectancy, quality-adjusted life years and average discounted lifetime costs were 6.71 years, 4.55 and $21,429 (U.S. $20,843) for warfarin; 6.79 years, 4.64 and $25,760 (U.S. $25,060) for dabigatran; and 6.81 years, 4.68 and $27,003 (U.S. $26,274) for the LAA occlusion. Compared with warfarin, the incremental cost-effectiveness ratio was $46,560 (U.S. $45,302) for dabigatran and $41,565 (U.S. $40,443) for LAA occlusion, making LAA occlusion the most cost-effective option.
Singh et al noted that the model was sensitive to two parameters—the odds ratio for bleeding on aspirin and for stroke with the LAA closure device—which could bump LAA occlusion from its perch as the preferred option. “[T]he true estimates of the odds of these two parameters is likely well less than the upper limit utilized in our sensitivity analysis. Moreover, the cost-effectiveness of LAA occlusion is likely underestimated in our model,” they wrote, citing improvements in implantation techniques and a decrease in complications since publication of the trials.
They added that outcomes in real-world practice may differ from clinical trial results, as might outcomes in patients younger than their simulated cohort. Results also might not apply to other healthcare delivery models.